Answers for "impory component vue in your App.vue file"

vue import component

// With Vue 3.2 
<script setup>
import Btn from './components/Btn'
</script>

<template>
  <Btn />
</template>

registeing components in vue

import Sidebar from '../../components/sidebar/main.vue';
export default {
    props: [""],
    components: {
        'sidebar': Sidebar
    },
...